This is an application for funds to purchase a phosphorimager to be used in experiments vital to research being performed in the Departments of Biology and Botany at the University of Iowa. The equipment requested includes image plates, laser scanner, work stations, printer, tape and disk storage devices, and appropriate software for image processing and analysis. The proposed instrument will comprise an integrated system that will be housed in the Biology Electron Microscope Facility, which is a departmental facility available to all faculty, students and staff in the Departments of Biology and Botany. Over thirteen researchers involved in nineteen NIH-funded research grants will utilize the requested equipment for a wide range of biological applications ranging from quantitative analysis of DNA-protein interactions to determination of sites of gene expression to DNA sequence analysis. The primary advantage of the phosphor imager system is that it eliminates the need for conventional autoradiography, allowing marked increases in efficiency together with significant reductions in cost of materials and disposal of radioactivity and heavy metals associated with film processing. In addition to increasing efficiency, the increased sensitivity of the instrument will allow researchers to make new observations and develop new research directions. Support for purchase of the proposed instrument would allow for a type of analysis not currently present at the University of Iowa.